Field of the Invention
The present invention relates to a radiation imaging apparatus and a control method of the same.
Description of the Related Art
A radiation imaging apparatus includes a sensor array for detecting radiation, a readout unit for reading out image data from the sensor array, and a processing unit for processing the image data. The processing unit performs, for example, offset correction for removing an offset component (noise component) from the image data. More specifically, this offset correction is performed by using image data (to be referred to as “offset data” hereinafter) read out from the sensor array while the sensor array is not irradiated. The offset data is obtained before offset correction is performed, and updated if the environment changes (for example, if the temperature changes or a predetermined time elapses).
When obtaining offset data after radiation imaging, a signal component of the radiation imaging may remain as an image lag (a residual image) in the offset data. Japanese Patent Laid-Open No. 2010-42150 has disclosed a technique of determining whether an image lag remains in image data, and employing the image data as offset data if no image lag remains.
Some radiation imaging apparatuses have a plurality of operation modes different from each other in time required to obtain image data of one frame (or an obtained frame count (frame rate) per unit time). In a radiation imaging apparatus like this, an offset component contained in image data changes when the operation mode is changed. Therefore, offset correction is performed by using offset data corresponding to each operation mode. This requires a technique which obtains (or updates) offset data for each operation mode within a short time.